The present invention is related to a method for testing an electronic unit mounted on an automobile by using a predetermined test apparatus, which on-vehicle electronic unit is equipped with a plurality of input circuits connected to a plurality of external switches, into which operation signals of the respective external switches are entered; a plurality of output circuits for outputting predetermined output signals to an external unit; and a control unit for controlling said respective output signals derived from said plural output circuits in response to said respective operation signals entered via said plural input circuits.
Conventionally, when an electronic unit is tested, more specifically, a shipping test of the electronic unit is carried out, with respect to functions actually provided with the electronic unit, input logic of switches is made up on the side of the test apparatus so as to perform the test.
For instance, as shown in FIG. 9, a confirmation of a door locking function in an automobile is performed as follows. A switch control signal (SW control signal: FIG. 10(a)) is sent out from the test apparatus 1 so as to turn ON/OFF a door locking switch 2, a high (H)/low (L) signal (FIG. 10(b)) derived from this door locking switch 2 is entered into an electronic unit 3. In response to this high/low switch, a confirmation is made as to whether or not the electronic unit 3 drives a door locking motor 4. The test is carried out as to whether or not the input circuits, the CPU, the output circuits, and the like employed in the electronic unit 3 are operated under normal conditions in accordance with the above-described test manner.
Also, as shown in FIG. 11, in an electronic unit for mounting an on-vehicle LAN, after the electronic unit 3 has been set in a test mode in accordance with a preselected input sequence, while using a communication input/output interface 5 for the on-vehicle LAN provided in this electronic unit 3, arbitrary switch input information is transmitted as serial data from the test apparatus 1 to the communication input/output interface 5. Since such a test method is carried out, it is possible to perform the test as to whether or not the CPU and the output circuits provided in the electronic unit 3 are operated under normal condition by confirming as to whether or not the electronic unit 3 drives the door locking motor 4 in response to the information contained in the serial data even when the switch 2 is not turned ON/OFF. Also, in this case, the input circuits employed in the electronic unit 3 are tested in such a manner that arbitrary serial data is transmitted from the test apparatus 1 to the communication input/output interface 5 of the electronic unit 3, and furthermore, this input information is returned from the electronic unit 3 as serial data to the test apparatus 1. In accordance with this test method, since the plural input circuits and the plural output circuits can be tested one time, the test time can be advantageously shortened.
It should be noted that reference numeral 6 shown in FIG. 9 and FIG. 11 represents a voltage measuring device for measuring a voltage applied to the electronic unit 3.
FIG. 12 is a detailed block circuit for representing the electronic unit 3 contained in the circuit block shown in FIG. 9. A test for the electronic unit 3 shown in FIG. 12 is carried out by separately turning ON/OFF a plurality of switches 2a to 2f by a shipment test apparatus 1. Among these switches 2a to 2f, symbol 2a indicates an ignition switch; symbol 2b shows a powered window up switch; symbol 2c represents a powered window down switch; symbol 2d denotes a door locking switch; symbol 2e shows a door unlocking switch; and symbol 2f represents a door switch. The ignition switch 2a is connected to an ignition switch input circuit (IG-SW input circuit) 11 provided in the electronic unit 3. The powered window up switch 2b is connected to a powered window up switch input circuit (POWER-WINDOW-UP-SW input circuit) 12 employed in the electronic unit 3. The powered window down switch 2c is connected to a powered window down switch input circuit (POWER-WINDOW-DOWN-SW input circuit) 13 employed in the electronic unit 3. The door locking switch 2d is connected to a door locking switch input circuit (DOOR-LOCK-SW input circuit) 14 employed in the electronic unit 3. The door unlocking switch 2e is connected to a door unlocking switch input circuit (DOOR-UNLOCKING-SW input circuit) 15 provided in the electronic unit 3. Then, the door switch 2f is connected to a door switch input circuit (DOOR-SW input circuit) 16 employed in the electronic unit 3. Also, the signals derived from these input circuits 11 to 16 are entered into a control unit (microcomputer chip) 17 containing a ROM, a RAM, and a CPU. While a dome (ceiling) lamp circuit 18, a door locking output circuit 19, a door unlocking output circuit 20, a powered window up output circuit 21, and a powered window down output circuit 22 are controlled by this microcomputer 17, the dome lamp 23, the door locking motor 4a, and the powered window motors 4b are driven, respectively. It should be understood that in FIG. 12, reference numeral 24 denotes a power supply circuit, and reference numeral 25 represents a watch dog circuit for testing a power supply level, and a run-away of the microcomputer 17.
Then, for example, in the case that both the powered window up switch input circuit 12 and the powered window up switch output circuit 21 are tested, after the ignition switch 2a is turned ON as shown in FIG. 13(a) by outputting a signal from the shipment test apparatus 1, the powered window up switch 26 is subsequently turned ON as represented in FIG. 13(b). The test can be carried out as to whether or not the powered window up output circuit 21 is turned ON under normal condition as shown in FIG. 13(c) by checking as to whether or not the power window motor 4b is driven in response to turning-ON of the powered window up switch 2b.
Also, FIG. 14 is a detailed block diagram for indicating the electronic unit 3 contained in the circuit block shown in FIG. 11. While the electronic unit 3 shown in FIG. 14 is tested, the on-vehicle LAN input/output interface (I/F) 5 exclusively used for testing purposes is installed in the electronic unit 3, and arbitrary switch input information is transmitted in the serial communication from the shipment test apparatus 1 to this on-vehicle LAN input/output interface (I/F) 5. As a result, even when no input signals are entered from the respective switches 2a to 2f, the electronic unit 3 can test the respective output circuits 18 to 22 by confirming that the output in accordance with the serial communication information is executed. Also, while the respective switches 2a to 2f are arbitrarily turned ON/OFF by the shipment test apparatus 1, the arbitrary switch inputs are made in the respective input circuits 11 to 16, and this input information is returned from the output interface 5 of the electronic unit 3 to the shipment test apparatus 1 in the form of serial data. As a result, testing of the respective input circuits 11 to 16 can be carried out. In accordance with this test method, a plurality of input circuits 11 to 16 and also a plurality of output circuits 18 to 22 can be tested within one time.
Very recently, while various sorts of electronic technology has been progressed, various functions provided in automobiles are considerably increased. In connection with this increase of functions, the control circuits employed in the electronic unit 3 are similarly increased. As a result, in accordance with the conventional test method for testing the respective switch inputs and the respective output controls the testing time is increased, and the production ????? is increased, which would induce deteriorations in productivity.
As indicated in FIG. 11 and FIG. 14, if such an electronic unit 3 for mounting the on-vehicle LAN is available, then the test time can be shortened by executing the test method with employment of the communication interface 5 while utilizing the serial communication. However, practically speaking, the electronic unit 3 for mounting the on-vehicle LAN is not so popular.
As a consequence, with respect to such an electronic unit 3 on which the on-vehicle LAN is not mounted, as indicated in FIG. 9 and FIG. 12, the actual input logic signals are entered to the electronic unit 3 by manipulating the switches 2a to 2f so as to test the respective input circuits 11 to 16 and the respective output circuit 18 to 22. Thus, the testing method for performing the test between the electronic unit 3 and the test apparatus 1 by using the serial communication could not be employed.
Alternatively, an interface circuit specific to a test purpose may be additionally employed in the electronic unit 3 on which no on-vehicle LAN is mounted as indicated in FIG. 9 and FIG. 12. In this specific case, there are problems that this electronic unit 3 would become large scale and would require high cost.